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Discussion Starter · #1 ·
Re: [EVDL] SRJC student's Focus-conversion-EV burned to its metalframe

OK, we've got a double negative, so I'm not sure what you meant, Pete! did
you mean that all the fires were on systems that DID have a BMS, or ones
that did NOT have a BMS system? Or did you mean something else entirely?

Joseph H. Strubhar

Web: www.gremcoinc.com

E-mail: [email protected]x



----- Original Message -----


From: "gottdi" <[email protected]>
To: <[email protected]>
Sent: Sunday, March 20, 2011 4:17 PM
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe


> There is one thing that can be said for sure. Not a singe electric vehicle
> fire has been without a BMS system. One for sure was controlling the
> BRUSA.
> It is not hard to come up with an educated guess that the problems lie in
> the controlling systems added to PROTECT the cells and control the
> chargers.
> It does not take a rocket scientist to figure this one out. But to be sure
> so every one is clear you will have to ask the folks who built it.
>
> Pete :)
>
> How many will it take before people will get it.
>
> -----
> If you don't understand, be patient, you will. Now I understand. :)
> --
> View this message in context:
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/SRJC-student-s-Focus-conversion-EV-burned-to-its-metal-frame-tp3390927p3392181.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
>
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Discussion Starter · #2 ·
Re: [EVDL] SRJC student's Focus-conversion-EV burned to its metalframe

Pete,

You are wrong.
I do not know how long you follow the EV world, but I know for sure
of an EV fire in Petaluma that nearly burned down a house, the owner
incidentally had his BMW outside charging the SLA batteries and it
burned
without him ever noticing until it was gone.
Please search the archives and you will find this and other examples
*without* BMS.
Not every BMS is evil, though there are bad ones, often due to the
*system* not properly working together (charger not cutting back
for example)
But there are enough things going wrong without ever a BMS involved.
It appears that this fire is yet another example as the last I heard
was that although a BMS was planned, it was not connected yet....

One thing that I am interested in is if the 90 cells were connected
in parallel or a long series string (about 300V system?)
The conclusion after the BMW fire was that the buddy-pairing may
have contributed to the fire, although I think that the source
of the fire was never found.
That owner also used an Iota 110AC power supply on a 196V DC system....

Regards,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of gottdi
Sent: Sunday, March 20, 2011 4:17 PM
To: [email protected]
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe

There is one thing that can be said for sure. Not a singe electric
vehicle fire has been without a BMS system. One for sure was controlling
the BRUSA.
It is not hard to come up with an educated guess that the problems lie
in the controlling systems added to PROTECT the cells and control the
chargers.
It does not take a rocket scientist to figure this one out. But to be
sure so every one is clear you will have to ask the folks who built it.

Pete :)

How many will it take before people will get it.

-----
If you don't understand, be patient, you will. Now I understand. :)
--
View this message in context:
http://electric-vehicle-discussion-list.413529.n4.nabble.com/SRJC-studen
t-s-Focus-conversion-EV-burned-to-its-metal-frame-tp3390927p3392181.html
Sent from the Electric Vehicle Discussion List mailing list archive at
Nabble.com.

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Discussion Starter · #3 ·
Re: [EVDL] SRJC student's Focus-conversion-EV burned to its metalframe

Then there are the vehicles that burned while underway.
Dave Cloud's 10-ETEK-powered Geo that caught fire at the end of the PIR
dragstrip a few years back comes to mind.
This was due to a lead-acid battery letting loose its smoke as I recall.
Three lead-acid batteries popped that night in 3 separate racers---none of
which happened during charging, but only 1 thankfully caught fire.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Cor van de Water
Sent: Monday, March 21, 2011 1:17 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe

Pete,

You are wrong.
I do not know how long you follow the EV world, but I know for sure
of an EV fire in Petaluma that nearly burned down a house, the owner
incidentally had his BMW outside charging the SLA batteries and it
burned

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| Multiple-address or CCed messages may be rejected.
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Discussion Starter · #4 ·
Re: [EVDL] SRJC student's Focus-conversion-EV burned to its metalframe

Was there a precharge resister on the controller that wasn't switched off,
maybe? If anybody can figure it out, it's Peter! This is a learning
experience. We've all made a few sparks along the way, I know I have!
;>)----- Original Message -----
From: "Mike Willmon" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Monday, March 21, 2011 7:24 PM
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe


> Yes but just like you said you like to make decisions based on facts,
> there are not yet enough now for you to draw that conclusion. It may
> be just as likely that a wrench or a screw driver accidentally
> dropped into the battery box or that someone with a vendetta came in
> and crowbarred a cell. Or like you speculate maybe someone was in the
> process of hooking up the charger and accidentally left it on before
> being fully tested or checked. For me the blame of "BMS causes fires"
> is extremely premature. I knowt you could go find many more accounts
> of lead acid cars with no BMS catching on fire as well. I've had
> BMS's on and off my truck, and in no case either with or without have
> I burned my truck down, not even once. There are plenty of Lithium
> powered cars too with and without BMS' that haven't burned the car
> down either. So without further detail and investigation which we
> were told has just now begun I think its a little premature to point
> to a conclusion that BMS' cause fires.
>
> Mike
>
>
gottdi <[email protected]> wrote:
>> Its not hard to see that all the recent fires that have resulted in total
>> destruction do have a common factor and it is not hard to deduct that
>> there
>> was an active process happening during the unattended time frame when the
>> cars burned. One thing for sure is that all the cars were unattended. My
>> car
>> sits unattended with lithium cells installed and since there is no active
>> processes happening there is no discharge of my cells and there has been
>> no
>> fires either or even any electrical component getting or even warm while
>> sitting. Something was happening and no matter what Pete Oliver said or
>> what
>> the reporters said some active process was happening. That is pretty easy
>> to
>> conclude that the car was charging. Pete was not there nor was he
>> involved
>> directly. He was only told what someone else said. I find it very hard to
>> believe that the car just burst into flame on its own with no active
>> process
>> happening. Something was ON. Someone is not being forthcoming. So
>> circumstantial evidence from what we know from all the fires like this
>> one
>> it is not hard to conclude that the car did have a BMS system installed
>> and
>> that the charger was ON. It is not a willy nilly observation and it is
>> quite
>> conclusive.
>>
>> There is no argument. There is a problem and it is COMMON to ALL the
>> fires
>> that have occurred in the past couple years.
>>
>> Also the fires being talked about are the ones where they were left
>> unattended and using lithium cells. Not cars at the race track bustin the
>> limits of the batteries and motors and controllers nor the EV's that are
>> lead acid.
>>
>>
>> Pete :)
>>
>> Sorry that you don't agree but it is no longer a coincidence. It is no
>> longer a small stupid mistake. There is a common factor. BMS or some
>> other
>> common factor but the problem is there. So we say BMS it brings to focus
>> that a problem exists and it is easy to see that something is amiss.
>>
>> With cars reduced to ash what do you do? Just toss your hands up or draw
>> conclusions from past fires of similar circumstances. You must trouble
>> shoot
>> the issue. And all you have is a pile of ash and someones word. I prefer
>> to
>> look at the evidence and not the words. People do lie to cover up
>> problems.
>> That is quite likely just as it is easy to draw the conclusion that power
>> was ON.
>>
>>
>>
>> -----
>> If you don't understand, be patient, you will. Now I understand. :)
>> --
>> View this message in context:
>> http://electric-vehicle-discussion-list.413529.n4.nabble.com/SRJC-student-s-Focus-conversion-EV-burned-to-its-metal-frame-tp3390927p3395280.html
>> Sent from the Electric Vehicle Discussion List mailing list archive at
>> Nabble.com.
>>
>> _______________________________________________
>> | REPLYING: address your message to [email protected] only.
>> | Multiple-address or CCed messages may be rejected.
>> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>> | OTHER HELP: http://evdl.org/help/
>> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>>
>
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Discussion Starter · #5 ·
Re: [EVDL] SRJC student's Focus-conversion-EV burned to its metalframe

If they had the batteries in buddy pairs, this could be a possibility.
Old post from John Wayland.

The triple stack of series strings is a great idea. Do not do them in
triple buddied pairs, just three separate strings that are normally
'not' paralleled at rest and only get paralleled just before keying on.
I did this with my twin strings in the Zombie for safety reasons.
Especially when drag racing and really pulling the batteries down hard
and getting them hot, as they later cool down they 'can' go bad and have
internal cell failures. If left in a series string unattached to other
series strings this causes no problem at all (until the next morning
when you test and see that a string might be sitting too low). Imagine
however, if all three strings were in hard-wired parallel. If one
battery goes down and becomes a 10V battery instead of a 12V battery,
with other strings at high voltage connected, the damaged cell is now
being force-charged and gets cooked to very high temps - this could
cause a fire overnight in your garage! This is the sole reason why I had
my twin strings always separated until run time in the Zombie. The
negatives of both packs were tied together, but the positive sides each
had a Kilovac EV250 contactor that would tie them together when
powering-up the car. Each pack was individually fused as well.

Details and photos here:
<http://www.plasmaboyracing.com/history/2007e.php>

I never had to use BMS of any kind with my Hawkers, but then again, I
always babysat the packs and would always do a post-racing EQ charge at
1/2 - 1 amp to get them all equal. If you keep the max. current to 750
amps (700 is even better), the batteries survive quite well.

Please keep us informed on this exciting project!

See Ya...John Wayland



-----Original Message-----
From: Bob Martin [mailto:[email protected]]
Sent: Monday, March 21, 2011 10:54 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe

Was there a precharge resister on the controller that wasn't switched
off,
maybe? If anybody can figure it out, it's Peter! This is a learning
experience. We've all made a few sparks along the way, I know I have!
;>)----- Original Message -----
From: "Mike Willmon" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Monday, March 21, 2011 7:24 PM
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe


> Yes but just like you said you like to make decisions based on facts,
> there are not yet enough now for you to draw that conclusion. It may
> be just as likely that a wrench or a screw driver accidentally
> dropped into the battery box or that someone with a vendetta came in
> and crowbarred a cell. Or like you speculate maybe someone was in the
> process of hooking up the charger and accidentally left it on before
> being fully tested or checked. For me the blame of "BMS causes fires"
> is extremely premature. I knowt you could go find many more accounts
> of lead acid cars with no BMS catching on fire as well. I've had
> BMS's on and off my truck, and in no case either with or without have
> I burned my truck down, not even once. There are plenty of Lithium
> powered cars too with and without BMS' that haven't burned the car
> down either. So without further detail and investigation which we
> were told has just now begun I think its a little premature to point
> to a conclusion that BMS' cause fires.
>
> Mike
>
>
gottdi <[email protected]> wrote:
>> Its not hard to see that all the recent fires that have resulted in
total
>> destruction do have a common factor and it is not hard to deduct that

>> there
>> was an active process happening during the unattended time frame when
the
>> cars burned. One thing for sure is that all the cars were unattended.
My
>> car
>> sits unattended with lithium cells installed and since there is no
active
>> processes happening there is no discharge of my cells and there has
been
>> no
>> fires either or even any electrical component getting or even warm
while
>> sitting. Something was happening and no matter what Pete Oliver said
or
>> what
>> the reporters said some active process was happening. That is pretty
easy
>> to
>> conclude that the car was charging. Pete was not there nor was he
>> involved
>> directly. He was only told what someone else said. I find it very
hard to
>> believe that the car just burst into flame on its own with no active
>> process
>> happening. Something was ON. Someone is not being forthcoming. So
>> circumstantial evidence from what we know from all the fires like
this
>> one
>> it is not hard to conclude that the car did have a BMS system
installed
>> and
>> that the charger was ON. It is not a willy nilly observation and it
is
>> quite
>> conclusive.
>>
>> There is no argument. There is a problem and it is COMMON to ALL the
>> fires
>> that have occurred in the past couple years.
>>
>> Also the fires being talked about are the ones where they were left
>> unattended and using lithium cells. Not cars at the race track bustin
the
>> limits of the batteries and motors and controllers nor the EV's that
are
>> lead acid.
>>
>>
>> Pete :)
>>
>> Sorry that you don't agree but it is no longer a coincidence. It is
no
>> longer a small stupid mistake. There is a common factor. BMS or some
>> other
>> common factor but the problem is there. So we say BMS it brings to
focus
>> that a problem exists and it is easy to see that something is amiss.
>>
>> With cars reduced to ash what do you do? Just toss your hands up or
draw
>> conclusions from past fires of similar circumstances. You must
trouble
>> shoot
>> the issue. And all you have is a pile of ash and someones word. I
prefer
>> to
>> look at the evidence and not the words. People do lie to cover up
>> problems.
>> That is quite likely just as it is easy to draw the conclusion that
power
>> was ON.
>>
>>
>>
>> -----
>> If you don't understand, be patient, you will. Now I understand. :)
>> --
>> View this message in context:
>>
http://electric-vehicle-discussion-list.413529.n4.nabble.com/SRJC-studen
t-s-Focus-conversion-EV-burned-to-its-metal-frame-tp3390927p3395280.html
>> Sent from the Electric Vehicle Discussion List mailing list archive
at
>> Nabble.com.
>>
>> _______________________________________________
>> | REPLYING: address your message to [email protected] only.
>> | Multiple-address or CCed messages may be rejected.
>> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>> | OTHER HELP: http://evdl.org/help/
>> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>>
>
> _______________________________________________
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Discussion Starter · #6 ·
Re: [EVDL] SRJC student's Focus-conversion-EV burned to its metalframe

At the risk of putting fuel on the BMS fire, it does deserve noting that all
it would take is one cell's BMS failing shorted to cause a cell to be very
unhappy and perhaps cause a fire. Assuming a battery pack that was not
being charged, but did have a BMS board across each cell, the probability of
BMS-short is equal to the number of these units times the probability that a
BMS could short. My guess is most of these BMS's don't spec those chances.

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Discussion Starter · #7 ·
Re: [EVDL] SRJC student's Focus-conversion-EV burned to its metalframe

So let's hypothesize.

A BMS shorts. This would typically mean that the fet, transistor or relay
failed closed. There would typically be a load resistor. The load resistor
would be sized for the full curren of the BMS of that cell, say 5 amps. Te
resistor would also be sized to not heat beyond 70degC at full load. If the
cell were a 100 amp cell the cell would be dead in 20 hours. Being in series
it would have no effect on the other cells.

I don't see it. Please give my your hypothesis of how the BMS could fail so
shorted that it would cause this fire instead of the speculation that "The
BMS did it".


Sincerely,
Mark Grasser


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Myles Twete
Sent: Wednesday, March 23, 2011 1:28 PM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe

At the risk of putting fuel on the BMS fire, it does deserve noting that all
it would take is one cell's BMS failing shorted to cause a cell to be very
unhappy and perhaps cause a fire. Assuming a battery pack that was not
being charged, but did have a BMS board across each cell, the probability of
BMS-short is equal to the number of these units times the probability that a
BMS could short. My guess is most of these BMS's don't spec those chances.

_______________________________________________
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Discussion Starter · #8 ·
Re: [EVDL] SRJC student's Focus-conversion-EV burned to its metalframe

I agree with your analysis, Mark, but I haven't studied BMS designs and
haven't done the FMEA on one.
My bet would be that few of these manufacturers, being small, have done a
full FMEA on their products.
One hypothesis: significant sliver of conductive material falls on the right
place on the PCB, turning the bypass current transistor ON and at the same
time as it offers a conductive path around its load. The transistor could
quick fail shorted (MosFET's do that) and if the conductive path thru it and
the shorted path on the PCB could sustain it, much higher currents could be
realized than just a 5amp bypass load. I don't know if there are
half-H-bridges in any BMS bypass outputs, but if so, that's another place
one would look. Or since the BMS is powered by the cell itself, perhaps the
input power stage is at risk of shorting. If one is thinking a wrench could
fall on the battery in the middle of the night, then certainly a much
smaller errant metal shaving could be involved.

Anyway, I didn't want to fuel the argument that a BMS was at all involved
here...just wanted to point out that IF a BMS could fail shorted, then even
a non-charging, non-connected pack could be damaged by these devices.

-mt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Mark Grasser
Sent: Wednesday, March 23, 2011 10:46 AM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe

So let's hypothesize.

A BMS shorts. This would typically mean that the fet, transistor or relay
failed closed. There would typically be a load resistor. The load resistor
would be sized for the full curren of the BMS of that cell, say 5 amps. Te
resistor would also be sized to not heat beyond 70degC at full load. If the
cell were a 100 amp cell the cell would be dead in 20 hours. Being in series
it would have no effect on the other cells.

I don't see it. Please give my your hypothesis of how the BMS could fail so
shorted that it would cause this fire instead of the speculation that "The
BMS did it".


Sincerely,
Mark Grasser


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Myles Twete
Sent: Wednesday, March 23, 2011 1:28 PM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe

At the risk of putting fuel on the BMS fire, it does deserve noting that all
it would take is one cell's BMS failing shorted to cause a cell to be very
unhappy and perhaps cause a fire. Assuming a battery pack that was not
being charged, but did have a BMS board across each cell, the probability of
BMS-short is equal to the number of these units times the probability that a
BMS could short. My guess is most of these BMS's don't spec those chances.

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| Multiple-address or CCed messages may be rejected.
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Discussion Starter · #9 ·
Re: [EVDL] SRJC student's Focus-conversion-EV burned to its metalframe

MT,
Absolutely, all possible. The commercial eurpean BMS I have looked at has
the BMS on the top of the cell as most do. Fuses are on both sides of the
BMS next to BOTH posts.

A point to make though. I would think that in a full short the cell would
have enough energy to burn the FET in two, blow off the lgs or fry the
traces.

On this one I am leaning toward the mm/volt theory. Grinding dust, saw dust,
almost anything could start the arc.

A step further, student gets done, locks the shop door and the furnace goes
on blowing air and dust etc.


Sincerely,
Mark Grasser



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Myles Twete
Sent: Wednesday, March 23, 2011 2:52 PM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe

I agree with your analysis, Mark, but I haven't studied BMS designs and
haven't done the FMEA on one.
My bet would be that few of these manufacturers, being small, have done a
full FMEA on their products.
One hypothesis: significant sliver of conductive material falls on the right
place on the PCB, turning the bypass current transistor ON and at the same
time as it offers a conductive path around its load. The transistor could
quick fail shorted (MosFET's do that) and if the conductive path thru it and
the shorted path on the PCB could sustain it, much higher currents could be
realized than just a 5amp bypass load. I don't know if there are
half-H-bridges in any BMS bypass outputs, but if so, that's another place
one would look. Or since the BMS is powered by the cell itself, perhaps the
input power stage is at risk of shorting. If one is thinking a wrench could
fall on the battery in the middle of the night, then certainly a much
smaller errant metal shaving could be involved.

Anyway, I didn't want to fuel the argument that a BMS was at all involved
here...just wanted to point out that IF a BMS could fail shorted, then even
a non-charging, non-connected pack could be damaged by these devices.

-mt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Mark Grasser
Sent: Wednesday, March 23, 2011 10:46 AM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe

So let's hypothesize.

A BMS shorts. This would typically mean that the fet, transistor or relay
failed closed. There would typically be a load resistor. The load resistor
would be sized for the full curren of the BMS of that cell, say 5 amps. Te
resistor would also be sized to not heat beyond 70degC at full load. If the
cell were a 100 amp cell the cell would be dead in 20 hours. Being in series
it would have no effect on the other cells.

I don't see it. Please give my your hypothesis of how the BMS could fail so
shorted that it would cause this fire instead of the speculation that "The
BMS did it".


Sincerely,
Mark Grasser


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Myles Twete
Sent: Wednesday, March 23, 2011 1:28 PM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] SRJC student's Focus-conversion-EV burned to its
metalframe

At the risk of putting fuel on the BMS fire, it does deserve noting that all
it would take is one cell's BMS failing shorted to cause a cell to be very
unhappy and perhaps cause a fire. Assuming a battery pack that was not
being charged, but did have a BMS board across each cell, the probability of
BMS-short is equal to the number of these units times the probability that a
BMS could short. My guess is most of these BMS's don't spec those chances.

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